Krishna Kakkera University of Arkansas for Medical Sciences, United States
Introduction: Amlodipine is a dihydropyridine calcium channel blocker (CCB) causing peripheral vasodilation with little effect on myocardium. We present a case of profound vasoplegic shock due to Amlodipine overdose that had a double peak in serum level and physiological toxicity.
Description: A 74-year-old female presented for altered mental status and hypotension after taking an extra dose of unknown medication for a systolic blood pressure of 180. Per patient and family she was on Valsartan, Verapamil, Amlodipine, Hydrochlorothiazide and Metoprolol.
On arrival she was profoundly hypotensive and hyperglycemic. She was treated for presumed CCB overdose with calcium gluconate and glucagon, but required maximally dosed Levophed, Vasopressin, Epinephrine, Angiotensin II, Phenylephrine and high dose insulin infusion titrated to 4.5units/kg/hour. This was followed by bolus dosing of methylene blue to which she had a brisk but transient response for about 24 hours which allowed us to wean vasopressors while maintaining MAPS above 65.
On day 3 her hemodynamics improved and she was on minimal vasopressors. On day 4, her vasoplegia worsened, requiring maximal doses of vasopressors and initiation of mechanical ventilation. Echocardiogram showed normal function so high dose insulin was stopped. Supportive care was continued in addition to broader spectrum antibiotics. She gradually improved and on day 7, she was off all vasopressors, extubated, and eventually discharged home. Her second decline was initially attributed to septic shock, but a post discharge Amlodipine level of 650 ng/dl on day 4 when compared to 190 ng/dl on day 1 led to multiple interesting conclusions.
Discussion: This patient required complex and dynamic resuscitation based on rapidly changing physiology. Normal cardiac function and lack of response to high dose insulin lowered our suspicion for Verapamil as the cause of her shock. The brisk response to methylene blue hinted at severe vasoplegia from Amlodipine overdose and adds to literature involving methylene blue as adjunctive therapy for Amlodipine overdose.
Lastly, the tremendous increase in serum Amlodipine level from admission to hospital day 4 reflects the prolonged half-life and unpredictable pharmacokinetics of drugs during toxic ingestions.
